Question

an electric bulb of 100W works for 4 hours a day .calculate the units oof energy consumed in 15 days

Answer 1

Power rating of the bulb:  100 W
Duration used each day:   4 hr
Number of days:               15

Total energy consumed by the electric bulb:  
     = power * duration
     = 100 W * 4 hrs/day * 15 days
      = 6000 W-hrs
      = 6 kWh

So energy consumed is  6 units.

Answer 2

Power of bulb = 100 W
Since it works for 4 hours per day so total power = 100 x 4 = 400 W

Each day , 400 W x 1 of energy is consumed
For 15 days , 400 x 15 = 6000 W-h energy is consumed.

6000 W-h = 6 Kwh = 6 units.

Hope This Helps You!